Take Arginine to Heart
Love may make your blood flow hot; arginine can make it flow more freelyBy Will Block

Don’t worry about your heart;
it will last you as long as you live.
— W. C. Fields

appy Valentine’s Day! Can you imagine February without it? How much poorer we all would be without a day on which to celebrate the joys of romantic love. Hearts and flowers and sinful chocolates and mushy sentiments—isn’t it wonderful? Even tattooed tough guys who eat nails for breakfast have been known to turn all gooey on Valentine’s Day. Their hearts, pierced by Cupid’s magic arrow, go pitter-patter at the thought of that special woman, the sweet object of their desire—even if, during the rest of the year, those same hearts just go lub-dub, lub-dub, in the decidedly unromantic jargon of the medical profession.

However it sounds, though, the important thing is that your heart keep on going and going, like the Energizer Bunny. After all, you want “as long as you live” to be a good long time, right? To maximize the chances of that, you should, of course, do all the right things: exercise regularly, eat sensibly, drink only in moderation, smoke not at all, avoid undue stress in your life (ha!), and take a judicious selection of nutritional supplements to help compensate for some of the common consequences of aging.

Blood Vessels Need Nitric Oxide, from Arginine

One such consequence is a gradual decline in the function of our circulatory system, whose job is not just to transport blood around the body. Our arteries must also ensure that the delivered blood supply is adequate for our cells’ needs and that our blood pressure remains within healthy bounds. These functions are governed in large part by the layer of flat, tightly packed endothelial cells that line the inner walls of the blood vessels and the heart.

Endothelial cells are metabolically active. Of the various chemical compounds they produce that affect vascular function, the most important is a signaling molecule called nitric oxide (NO), which is produced from its precursor molecule, the nutrient amino acid arginine. NO plays a key role in various aspects of cardiovascular function, one of which is to regulate the size of the lumen, or opening (the cross-sectional area) of the blood vessels, because this affects the rate of blood flow and the blood pressure.

Nitric Oxide Controls Blood Pressure

Think of a typical garden hose, which has an inner diameter of 5/8”. From experience, you know about how much water you can expect to get from that hose at full pressure. If you now switch to the slightly larger 3/4” size—only 1/8” (20%) larger in diameter—you will see a surprisingly large increase in flow rate at the same pressure, because the lumen of the hose is now 44% larger!* Seen from a different perspective, you can get the same flow rate as before at a lower pressure than before, because it requires less pressure to push a given amount of water through a hose of larger diameter.

*Remember that the area of a circle increases as the square of its radius, so any increase in the radius will always produce a disproportionately large increase in the area.

Your blood vessels are just like the garden hose, except that they can expand and contract automatically to accommodate your body’s frequently changing needs for blood flow to this region or that, while maintaining your blood pressure within a given range. The pressure must be high enough to ensure an adequate uphill flow of blood to your brain (thus avoiding blackouts), yet not so high that your blood vessels might be damaged, or even weakened to the point of bursting (a blowout).

Electron micrograph of an arteriole, showing the inner lining of endothelial cells, where NO molecules are generated in response to the need for dilation.

It’s a wonderful system, based on the ability of NO to dilate the blood vessels as needed. When NO molecules are produced in endothelial cells, they rapidly diffuse through the cell membrane into the underlying smooth muscle cells, inhibiting their contraction and causing them to relax. The resulting dilation of the blood vessel increases blood flow and decreases blood pressure. (See illustration.)

Hypertension Damages the Heart, and More

As we age, however, this aspect of endothelial function tends to degrade, usually as the result of inflammatory processes that damage the cells. With less NO being produced, the blood vessels become chronically constricted,* which leads to hypertension (high blood pressure). The heart must work harder than before to generate the higher pressure needed to keep the blood flowing at a rate that is sufficient to nourish all the body’s cells with life-giving oxygen and glucose. This puts undue strain on the heart and can take a severe toll in the long run. (And if the body’s cells are not properly nourished, owing to an inadequate blood supply, they suffer damage or death.)

*Note that constriction means a generalized narrowing of the whole blood vessel, not a localized narrowing caused by an obstruction, such as atherosclerotic plaque—that’s a separate (but related) story.

About 10% of all cases of hypertension are the result of some underlying disease; in the other 90% of cases, the root cause is unknown. In any case, though, the effect is always bad. Hypertension is a major risk factor for heart attack and stroke (“brain attack”), and even in the absence of such catastrophic events, it can cause serious damage to these organs, as well as to the blood vessels, kidneys, and eyes.

Nitric Oxide Helps Prevent Atherosclerosis

As if hypertension weren’t bad enough, endothelial dysfunction also promotes the formation of blood clots and of artery-clogging plaque deposits (atherosclerosis), which further restrict blood flow and can lead to a heart attack. In fact, the magnitude of endothelial dysfunction in the coronary arteries is a potent predictor of major cardiovascular events—notably heart attack, coronary revascularization (surgical intervention on diseased arteries, such as a bypass graft), and cardiac death.1 And even when it falls short of such extremes, heart disease often impacts other aspects of our health, such as sexual function (see the sidebar “The Heartbreak of Impotence”).

The Heartbreak of Impotence

It’s good that the symbol of Valentine’s Day is the heart, with all that it traditionally implies about romantic love and devotion. It could have been the rather less attractive brain, which is, of course, where all thoughts and emotions actually reside (the heart merely reacts to what’s going on upstairs). Or it could have been . . . no, it couldn’t—that would be most unseemly, even if it is an acceptable image (an object of worship, even) in some cultures of the world.

Whether you think that sex as the ultimate expression of love exists mainly to give us pleasure or solely to facilitate procreation, one thing is for sure: it doesn’t work very well without the full cooperation of what Robin Williams refers to as “Mr. Happy.” When Mr. Happy fails to rise to the occasion, whether on Valentine’s Day or any other time, he makes a mockery of his own name, and the result can be heartbreaking.

Actually, a heart that is “broken,” in a sense, is a warning sign for impotence, and vice versa, according to medical researchers at the Mayo Clinic in Rochester, Minnesota.1 Their long-running epidemiological study of 2000 men aged 40 to 79 revealed a strong link between heart disease and impotence. Men who had a heart attack during the period 1979–1995 turned out to be 3.5 times more likely than heart-healthy men to have problems with impotence in 1996. The researchers concluded not only that cardiovascular disease is a significant risk factor for impotence—which had been known for decades—but also that impotence is a “marker” (indicator) for future cardiovascular disease.

The link between the two conditions is strong: the same major risk factors for a dysfunctional heart—lack of exercise, high blood pressure, high cholesterol, obesity, diabetes, and smoking—are also associated with a dysfunctional penis. It’s no accident that Viagra® was initially tested as a drug to fight heart disease involving narrowing of the blood vessels. When its intriguing “front effect” was reported by delighted male patients, the proverbial light bulb (or was it a dollar sign?) went on over the researchers’ heads, and the rest is history.

Viagra works against impotence because it indirectly enhances the effects of nitric oxide, the molecule that dilates blood vessels and allows greater blood flow to regions that need it. The nutrient amino acid arginine is a natural, and safer, alternative to Viagra because it is the direct chemical precursor of nitric oxide in the human body (see “A Natural Alternative to Viagra” in Life Enhancement, April 2001).

Because endothelial dysfunction contributes to atherosclerosis, and because the increased bioavailability of nitric oxide counteracts endothelial dysfunction, NO is considered to be antiatherogenic, i.e., it helps prevent atherosclerosis. And since it has long been known that endothelial function declines with age, the importance of having adequate compensatory supplies of arginine, the precursor of NO, increases with age, even when there are no symptoms (yet) of cardiovascular disease. Furthermore, cholesterol-lowering and antioxidant therapies can also improve the bioavailability of NO, for a dual cardiovascular benefit that may help explain the reduced risk for cardiac events associated with these interventions.2

Healthy Elderly Have Poor Endothelial Function

A group of German researchers decided to investigate the role of supplemental arginine in improving endothelial function in the healthy elderly, using as their test subjects 12 men and women (aged 70–78, average 74) with no signs of cardiovascular disease or significant risk factors for it.3 Despite their generally good health, the subjects’ level of endothelial function was very poor compared with that of healthy young adults—a situation that did not bode well for their long-term health.

In a randomized, double-blind, placebo-controlled crossover study, the researchers tested the effects of oral arginine (8 g twice daily for 14 days) on the ability of the brachial artery (the main artery of the arm) to dilate in response to increased blood flow, a stimulus that triggers the endothelial cells’ release of NO. The increase in blood flow was effected by the simple means of restricting it for 5 minutes with a pneumatic tourniquet on the forearm, then suddenly releasing the tourniquet to allow the blood to flow freely again. The diameter of the brachial artery was measured using high-resolution ultrasound imaging.

Arginine Greatly Improves Vascular Dilation

The results showed that 2 weeks of arginine supplementation doubled the flow-mediated dilation of the brachial artery in the elderly subjects, from one-quarter the amount of dilation normally experienced by healthy young adults to one-half that amount. The placebo, by contrast, had no significant effect. The authors pointed out that, according to existing evidence, this beneficial effect of NO-producing arginine appears to occur only in those with impaired endothelial function, i.e., primarily the elderly.

They suggested that the effect is probably due to a normalization of the body’s ratio of arginine to its “evil” cousin ADMA (asymmetric dimethylarginine), an inhibitor of NO production. The levels of ADMA increase with age, and they are an independent predictor of atherosclerosis in the carotid arteries;4 ADMA has also been identified as an independent cardiovascular risk factor.5,6 All the more reason to supplement with arginine, so as to offset the increases in ADMA and maximize the myriad benefits of nitric oxide in the body.*

At the beginning of this article are some prescriptions for maximizing the chances of living a long life. There’s one item, though—often overlooked, despite the abundance of evidence to support it—that we saved for last. It is this: love someone. One of the best things you can do for your heart is to give it to someone else. Studies have shown that people who are involved in other people’s lives through committed, loving relationships tend to be happier and healthier—and they tend to live longer—than those who are not. So here’s to love, in all its many-splendored glory!